The invention disclosed herein relates to improvements in track fittings of the type disclosed in Bentley U.S. Pat. No. 5,058,829, entitled "SEAT TRACK FITTING", which are commercially available from Weber Aircraft of Gainesville, Tex. Track fittings are employed for securing passenger seats in commercial and military aircraft to track rails in the floor of an aircraft. Track fittings vary in design due to the structural needs of the seat and the allowable strength of the aircraft.
Track rails in aircraft are generally "C" shaped channels and have holes bored every inch along the length of flanges to allow installation of the seats at any position and adjustment between seats at 1 inch increments along the track. The seat track fittings generally have track fitting lugs, arranged in pairs on the bottom of the fitting, which have an inverted "T" shaped cross section and have radii to allow them to be installed in the holes in the aircraft seat track rails.
The track fitting disclosed in Bentley U.S. Pat. No. 5,058,829 has a "C" shaped shear plunger mounted to slide vertically on the track fitting body. A separate "U" shaped anti-rattle device is moved by a screw to position ends of legs of the device in engagement with upper surfaces on the track to lift track fitting lugs into firm engagement with under surfaces of the track flanges.
Another fitting, disclosed in U.S. Pat. No. 4,771,969 entitled "LEG SET TRACK FITTING", is commercially available from Sabre Industries, Inc. of Burbank, Calif. The fitting has a generally circular shear element, which pivots about a horizontal axis relative to one end of a finger extending into the groove in a track such that the shear element is movable into openings in the track to prevent movement of the fitting longitudinally of the track. The fitting is also provided with a yoke configured to straddle the finger and extend into openings in the track to prevent sliding movement and to prevent rattling. This type of fitting, made of three stainless steel castings which require a 100% X-Ray inspection of the castings to satisfy Federal Aviation Regulations, is very expensive to manufacture and is very difficult to install.
An additional track fitting which is commercially available from Ancra Corporation of El Segundo, Calif. is disclosed in U.S. Pat. No. 4,256,424 entitled "RATTLE PROOF ANCHOR FITTING FOR SECURING LOADS TO A RETAINER TRACK". This fitting has a sliding shear plunger and a separate "U" shaped clamp member having flange surfaces which engage the track to prevent rattling.
Under certain conditions, track fittings of the type heretofore devised may be difficult to install because they must be in near perfect alignment with the seat track holes to engage properly. The fitting shear plunger must be snapped into the track hole and an adjustment screw must be turned to secure the anti-rattle device.
Some fittings utilize a single mechanism for the anti-rattle device and the shear plunger. However, this configuration is not the best, structurally, because the shear plunger is usually located between or aft of the fitting lug pairs. When the shear plunger is located between or aft of the fitting lug pairs, the track lip pairs that are forward of the shear plunger, react against both the shear plunger and one pair of fitting lug pairs in combination. Full track strength cannot be achieved in this configuration; however, this configuration is the easiest to access for installation and maintenance.
One track fitting which is commercially available uses a center plunger/antirattle device spring loaded in the up mode. The fitting is positioned over a hole in the track and a spring loaded adjuster is pushed down. The plunger drops down into the hole and the adjuster makes contact with mating threads in the fitting body.
The adjuster is tightened to produce a snug fit and a small grub screw is tightened against the adjuster to prevent loosening. The small grub screw on the side of the fitting is a time consuming operation to be performed after the fitting is installed. This operation can be carelessly overlooked causing a non-secure fit of the track fitting.
If the shear plunger of track fittings heretofore devised is not located correctly, and the antirattle device is tightened, the track fitting can give a false appearance of a positive structural installation. The installation and removal of a seat from an aircraft is very time consuming, which is hampered by the fitting installation. Once the seat is installed in an aircraft, and the fitting is tightened, there exists no means of identification for confirming positive engagement between the track fitting and the track.
Other track fittings are disclosed in U.S. Pat. Nos. 3,189,313; 3,620,171; 3,652,050; 3,677,195; 3,810,534; 4,026,218; 4,062,298; 4,109,891; 4,114,947; 4,396,175; 4,493,470; 4,509,888; 4,688,843; 4,708,549; 4,718,719 and 4,911,381.
When a track fitting is removed from the track, the threaded adjusting screws may be bent or lost along with other fitting pieces. Further, the requirement that several tools be employed for installing or removing seats is undesirable.
A track fitting with a visual identification is needed to ensure positive track engagement and to permit proper installation and removal of seats much more quickly than can be accomplished using track fittings of the type heretofore devised.